Jackson不会调用CustomContextResolver的getContext（）方法 [英] getContext() method of CustomContextResolver is not called by Jackson

问题描述

我几天来一直在努力解决这个问题，并且不知道如何解决这个问题。任何快速帮助将不胜感激。
我需要从JSON字符串转换LocalDate，我使用apache CXF和jackson从REST服务构建接收。我在Mapper对象中编写了自定义ContextResolver并注册了JavaTimeModule。
当我运行应用程序时，默认构造函数被调用，这意味着它已被加载，但返回ObjectMapper的getContext（）方法永远不会被调用。

I在服务器端和客户端注册了相同的ContextResolver。
所有依赖项都已到位（jackson数据绑定，核心，注释，数据类型-jsr310）。

当我直接点击REST URI时，我能够获取JSON响应在浏览器中。当我从客户端代码中调用相同的URI注释方法时出现问题
下面是我的客户端代码。

  import javax.ws.rs.ext.ContextResolver; 
 import javax.ws.rs.ext.Provider; 
 
 import com.fasterxml.jackson.databind.ObjectMapper; 
 import com.fasterxml.jackson.databind.SerializationFeature; 
 import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule; 
 
 
 @Provider //使这个bean成为Provider 
公共类LocalDateObjectMapperContextResolver实现ContextResolver< ObjectMapper> {
 
 private final ObjectMapper MAPPER; 
 
 public LocalDateObjectMapperContextResolver（）{
 MAPPER = new ObjectMapper（）; 
 MAPPER.registerModule（new JavaTimeModule（））; 
 MAPPER.configure（SerializationFeature.WRITE_DATES_AS_TIMESTAMPS，false）; 
} 
 
 @Override 
 public ObjectMapper getContext（Class<？> type）{
 return MAPPER; 
} 
 
} 
< jaxrs：client id =testclient
 serviceClass =package1.RESTService
 username =abc
 password =abc
 address =$ serviceURL> 
 
< jaxrs：features> 
< bean class =org.apache.cxf.transport.common.gzip.GZIPFeature/> 
< cxf：logging /> 
< / jaxrs：features> 
 
< jaxrs：providers> 
< bean class =org.codehaus.jackson.jaxrs.JacksonJaxbJsonProvider/> 
< bean class =mypackage.LocalDateObjectMapperContextResolver/> 
< / jaxrs：providers> 
 
< / jaxrs：client> 
  

同样，这个contextResolver也在服务器端注册

 < jaxrs：server> 
 ..... 
< jaxrs：providers> 
< bean class =org.codehaus.jackson.jaxrs.JacksonJaxbJsonProvider/> 
< bean class =mypackage.LocalDateObjectMapperContextResolver/> 
< / jaxrs：providers> 
< / jaxrs：server> 
  

没有调用getContext的原因是什么？

<我也尝试通过扩展ObjectMapper并在那里注册javaTimeModule，但是不知道如何在Jackson流程中注册customObjectMapper。我只是把默认构造函数用于测试，它确实在应用程序启动时被调用，但是再次，没有结果，我仍然得到相同的错误。

错误：没有合适的构造函数找到类型[simple type，class java.time.LocalDate]：无法从JSON对象实例化（需要添加/启用类型信息？）

解决方案

我有完全相同的问题@peeskillet描述了问题评论。

我使用的是版本2的Jackson依赖项和版本1的jackson-jaxrs。

将所有依赖项移动到版本2时全部解决。

I am struggling with this issue for days now and have no clue how to solve this. Any quick help will be grateful. I need to convert LocalDate from JSON string which I am receiving from REST service build using apache CXF and jackson. I wrote custom ContextResolver and registered JavaTimeModule in Mapper object. When I run the application, default constructor is called, that means it has been loaded, but getContext() method which returns ObjectMapper never gets called.

I have registered same ContextResolver in server and client side. All dependencies are in place(jackson databind, core, annotation, datatype-jsr310).

I am able to fetch JSON response when I hit REST URI directly in browser. Issue comes when I call same URI annotated method from client code Below is my client code.

import javax.ws.rs.ext.ContextResolver;
import javax.ws.rs.ext.Provider;

import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;


@Provider //makes this bean a Provider
public class LocalDateObjectMapperContextResolver implements ContextResolver<ObjectMapper>{

    private final ObjectMapper MAPPER;

    public LocalDateObjectMapperContextResolver() {
        MAPPER = new ObjectMapper();
        MAPPER.registerModule(new JavaTimeModule());
        MAPPER.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, false);
    }

    @Override
    public ObjectMapper getContext(Class<?> type) {
        return MAPPER;
    }

}
<jaxrs:client id="testclient"
    serviceClass="package1.RESTService"
    username="abc"
    password="abc"
    address="$serviceURL">

    <jaxrs:features>
        <bean class="org.apache.cxf.transport.common.gzip.GZIPFeature"/>
        <cxf:logging/>
    </jaxrs:features>

    <jaxrs:providers>
        <bean class="org.codehaus.jackson.jaxrs.JacksonJaxbJsonProvider"/>
        <bean class="mypackage.LocalDateObjectMapperContextResolver"/>
    </jaxrs:providers>

</jaxrs:client>

Same way, This contextResolver is registered on server side also under

<jaxrs:server>
.....
 <jaxrs:providers>
    <bean class="org.codehaus.jackson.jaxrs.JacksonJaxbJsonProvider"/>
            <bean class="mypackage.LocalDateObjectMapperContextResolver"/>
  </jaxrs:providers>
</jaxrs:server>

Any reason why getContext is not called?

I also tried by extending ObjectMapper and registering javaTimeModule there, but dont know how to register customObjectMapper in Jackson flow. I just put default constructor for testing, And it does get called while application startup, but then again, No results, I still get same error.

Error: No suitable constructor found for type [simple type, class java.time.LocalDate]: can not instantiate from JSON object (need to add/enable type information?)

解决方案

I had exactly the same problem @peeskillet describes in question comment.

I was using Jackson dependencies from version 2 and jackson-jaxrs from version 1.

All solved when moved all dependencies to version 2.

这篇关于Jackson不会调用CustomContextResolver的getContext（）方法的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！